New York Democrats have been known to co-opt the Charles Dickens concept of "A Tale of Two Cities."

Public Advocate Bill de Blasio currently uses it for his mayoral campaign. In a similar vein, past mayoral candidate Fernando Ferrer evoked the "other New York." Ex-Gov. Mario M. Cuomo went national in 1984 with "two cities" as the theme of his famous Democratic National Convention speech.

But there is also a lesser-known, nonpartisan story to be told -- a tale of two City Halls. One is all about public theater, usually driven by whoever is mayor, featuring spirited sound bites and spin.

Then there is the City Hall of important but unsexy public functions -- a City Hall populated by the likes of James F. Hanley, 64, the commissioner who heads the city's Office of Labor Relations.

The commissioner could play a crucial role next year, since departing Mayor Michael Bloomberg will leave his successor a term's worth of unsettled labor contracts.

In a city where every mayor or would-be mayor tries to come off as indispensable, it is notable that Hanley has been labor commissioner in the past four administrations, since Ed Koch -- and served in subordinate roles in the two before that.

"He's the one person who understands how to deal with more than 65 municipal union contracts," New York University Professor Mitchell Moss said.

Vincent Montalbano, a private consultant and former official of District Council 37, said, "Hanley has always been a good negotiator, and by that I mean, as Victor Gotbaum used to say, 'It's not called collective bargaining for nothing.' "

"He's not soft. He's a strong negotiator and advocate for the management side. I may not like that [as a union representative], but he's honest, and that's important in discussing things."

Bloomberg, who's legally barred from running again, hasn't reached contract pacts with unions for several years. So most municipal employees work under the automatically extended terms of expired pacts.

After 41 years on the scene, and with crucial negotiations due, will Hanley stay on for the next mayor, even if he falls back into his civil-service title? He said casually in a brief phone conversation between meetings Thursday: "I don't figure these things out until I get there."

Mayoral candidates generally do not comment in advance on who their commissioners would be -- even if Council Speaker Christine Quinn has said any mayor "would be lucky" to have Kelly as top cop. But Bloomberg's would-be successors appear well aware of the problems that await.

Comptroller John Liu, a mayoral candidate, blasted Bloomberg last month, saying, "This mayor is leaving the taxpayers deep in the red with personnel costs that should have been addressed a long time ago. We now have a situation with hundreds of thousands of city employees working without current contracts.